Process for the transformation of the interior structure of clouds

ABSTRACT

A process and apparatus for the transformation of the internal structure of visible cloud banks to induce rainfall or snow, or to avoid hail-storms, comprising igniting explosive compositions at time intervals of less than 25 seconds to create a sudden upward movement of energy directed to form shock waves at cloud level to modify the internal structure of the cloud banks.

United States Patent [191 Ollivier et al.

[ Nov. 19, 1974 PROCESS FOR THE TRANSFORMATION OF THE INTERIOR STRUCTURE OF CLOUDS [75] Inventors: Fred Ollivier; Gerald Ollivier, both of Manosque, France Pepro Societe Pour le Development et la Vente de Specialities Chemiques, Lyon, France [22] Filed: June 4, 1973 [21] Appl. No.: 367,008

[73] Assignee:

[30] Foreign Application Priority Data June 16, 1972 France 72.22941 Nov. 20, l972 France 72.41746 May 29, 1973 France 73.21153 [52] U.S. Cl. 239/2 R, 239/14 [51] Int. Cl E0lh 13/00 [58] Field of Search 239/2 R, 14

[56] References Cited UNITED STATES PATENTS 990,!21 4/l9ll Drake 239/2 R X 2,665,l68 l/l954 Kerlin 239/2 3.l35,466 6/1964 Reid 239/2 R X Primary ExaminerM. Henson Wood, .lr. Assistant ExaminerMichael Mar Attorney, Agent, or FirmBrowdy and Neimark 5 7] ABSTRACT A process and apparatus for the transformation of the internal structure of visible cloud banks to induce rainfall or snow, or to avoid hail-storms, comprising igniting explosive compositions at time intervals'oftless than 25 seconds to create a sudden upward movement of energy directed to form shock waves at cloud level to modify the internal structure of the cloud banks.

12 Claims, 6 Drawing Figures V//////////// ////V////W/////////// PATENTEL, 219V 1 91974 SHEH 20F 2 FIG. 4

FIG. 3

FIG. 5

FIG. 6

PROCESS FOR THE TRANSFORMATION OF THE INTERIOR STRUCTURE OF CLOUDS The present invention concerns a process for the transformation of the interior structure of clouds, permitting notably the avoidance of hail-storms, or the induction of rainfall or snow above plantations and crops.

More particularly, the invention concerns a process to combat hail by the formation of shock-waves created by explosions repeated at short-time intervals and obtained by the combustion within a burner of a product, or of a composition, liable to explode either directly, or by contact with the air, or with another product, or another composition, through sudden upward evacuation of the energy formed by means of a truncated chimney connected to the burner, the time interval separating two successive explosions being less than seconds.

The use of hail rockets is known. These function by ignition of a detonator which propels the rocket towards the cloud in the sky. This rocket contains a charge which explodes inside hail-cumulus or -cirrus clouds by means of a delayed-fuse device.

This process is not without danger; it is not always effective and requires the presence of qualified pyrotechnicians; furthermore the altitude of the clouds must be accurately known in order that the explosion occurs at the desired height.

Clouds, which are combinations of aqueous, luminous, and electric meteors, localize preferentially over flat land or shallow depressions which are therefore known as barometric morasses. It is hardly necessary to state here the continual inconveniences of storms and, more especially, hail-storms.

Repeated perturbations such as produced by a rather strong wind, displace and carry away hail clouds.

The present invention permits a modification of the internal structure of the clouds and simultaneously allows their displacement from the are which requires protection. In order to achieve this, a combustible gas stock is created. This gas passes into a burner by means of a controlled regulator valve. Ignition is carried out, and repeated, inside the burner. A pilot jet functions permanently during the storm but combustion can be accelerated by sudden abundant gas influx which, on each flow rate acceleration, gives rise to an explosion. Since the burner is turned towards the sky by means of a long chimney, the ignition is directed from the base towards the outlet, so that shock waves are induced.

The invention is noteworthy from the fact that different combustible gases can be used. The most general description of an apparatus for the working of the invention brings out the following:

1. Storage after manufacture 2. Gas-flow control by a valve 3. Combustion within a burner 4. Exhaust escape of the combustion products towards the sky.

Shock wave induced perturbation phenomena provoked by this anti-hail cannon, localized at the cloud level, are linked to this final phase; they will only be active in the case of rapid repetitions of the ignitions within the times specified hereafter.

The invention can best be understood by reference to the following description of non-limiting examples and by reference to the annexed drawings in which:

FIG. 1 is a schematic vertical cross section of an apparatus employed in the process of the present invention.

FIG. 2 is a schematic cross section of an apparatus representing an alternate embodiment of the present invention.

FIG. 3 is an enlarged view of the joint between the retracted narrow section of the burner and the truncated conical chimney circled in FIG. 2.

FIGS. 4 A, B, C are enlarged views of the possible positions of valve 37 in FIG. 2.

FIG. 5 is a flow diagram of the control system employed with the present invention.

FIG. 6 is a flow diagram of a modified control system employed with the present invention.

With reference to FIG. 1, 1 is a acetylene gas generator containing water and calcium carbide and in which the following chemical reaction takes place :C Ca 21-1 0 C I-I Ca(OI-I) The calcium hydroxide is periodically removed through valve 1a before recharging via valve lb. The tube 2 directs acetylene gas, in a crude state, through a flexible connection 2a, in rubher, into the scrubbing unit 3.

Inside the scrubber 3, the gas is forced to pass through the water bath by the walls of the syphon 4. The washed gas flows out through tube 5. The glass sight level 3a indicates the upward transfer of water under compulsion by the gas.

At the base, of syphon 4, the drain-plug 4a allows the periodic rinsing out of the apparatus and the removal of waste-products such as ammonia, hydrogen sulphide and chalk dust. A purification unit 6, fed by tube 5, contains water and washed gas. A funnel 6a enables the amount of water to be maintained.

The purge 6b allows the control of the water-level to ensure that the desired water level is maintained.

The gas bubbles its way through the water before passing into the purified gas inlet lead 7 to the flowcontrol outlet valve 8.

The How-control valve 8 in use, causes the gas to pass equally to the gas reservoir or storage IO by pipe 9, to the burner 13 by pipe II and the pilot-jet 11a, and to lead I2 for sudden and abundant volume return to the burner 13. At this point it should be understood that the valve 8 could be replaced by an inletand exhaustflow controlled rotary pump. This type of equipment is of current approved design. The switch-gear can be thermochemical, mechanical, electric, photoelectric or electronic.

The compartmented gas-holder 10 has an upper dome which assures the presence of gas under pressure. In effect, the gas pressure raises the holder dome from the base in an upward direction. Tube 9 allows outlet, inlet, or return gas-flow towards the valve 8. The term gas-holder 10 may be an inflammable gas storage tank.

It should be noted that the gas-buming process begins with various manipulations of the valve 8, ignition by the pilot 11a, and the entry of gas through I2 into the burner I3. The next phase, which is the sought after phase and repeated phase, is the exhaustion of combustion gases. Pipe II is a narrowed line which leads to a pilot 11a. The pilot is lit once at each approaching storm.

The burner 13, like all burners, is composed of a fresh-air inlet I3a at the base and a chimney 14 at the top. The burner is constructed in heavy-gauge sheet metal capable of withstanding the stresses provoked intermittently, or repeatedly, by the explosions directed towards the sky by burnings.

Chimney or diffuser 14 is in the form of a truncated cone open towards the sky. The assembly of the combustion apparatus I3 diffuseur 114 is, in the preferred form, very robust and anchored to the ground, for example, by steel anchor bolts. The successful use of the device is conditioned by the repetition at the hereinafter given frequency, of the violent explosions occurring in the burner, the energy thus liberated being propelled violently to high altitude by positioning a truncated conical chimney on the upper part of the explosion chamber.

According to one possible method of use of this invention, the explosions are obtained by combustion of a given mixture of acetylene and air.

The success of this process is furthermore conditioned by the existance of a certain number of means causing the propagation of an optimum shock wave.

The foremost, and most important, of these means concerns the explosion repetition frequency. This is a fundamental element in so far as it conditions the efficiency of the system.

Experience at different frequencies has proved that above a given frequency level the perturbation created at the cloud level was not sufficient to meet the soughtafter objective. Indeed, it is necessary to understand that the phenomena induced at the cloud level are progressive interval structural transformation phenomena, each shock wave participating in this transformation and to understand that the interval which separates the arrival of two waves must be sufficient to avoid the reversability of the energy transformation and the return of the cloud to its hail-producing structure.

Different studies carried out show that the frequency, defined in the present application as the maximum time-interval separating two explosions, must be less than 25 seconds and, in the preferred case, less than 15 seconds.

Above 25 seconds, the time-interval separating the arrival of two shock waves in the hail-forming cloud, is too high for the procedure to be really effective. Between 15 and 25 seconds, the process is effective but the transformation-time of the internal cloud structure is proportionately too long and the efficiency of the process, in the case where hail danger is particularly imminent, may not be sufficient. On the contrary, with firing frequencies of 15 seconds and, notably, for frequencies of 8 to 14 seconds, the efficiency of the process is at a maximum and spectacular results are obtained.

In certain cases, the effect obtained has even been curative. That is to say that repeated shots every 12 seconds during an existing hail storm, resulted, after several firings in a progressive transformation of the nature of the hail, since, the latter became less hard, tending progressively towards an entirely melted structure, in fact, rain.

Frequencies of less than 8 to 10 seconds can eventually be used but this leads to excessive consumption of gas and is therefore economically less viable. This frequency level can, however, be used where the hail risk is particularly threatening, with the object of obtaining an extremely rapid effect.

Generally speaking, frequencies between 10 and 12 seconds give rise to an optimum balance between maximum effect and minimum cost.

The second point, which is extremely important, consists in the presence in the lower part of the burner wall of at least one air inlet, comprising a prakis opening in the casing which is blocked during the explosion. Such a device can be constituted by a flap, free to move along its horizontal or vertical axis and of dimensions slightly greater than the orifice of the same shape, in the burner wall; the said flap falling over into the closed position against the inside burner wall so as to block the opening.

This air inlet, which serves to supply the air necessary for the combustion of the acetylene, and which also serves to allow a predetermined mixture of air and acetylene to be drawn into the burner, operates as follows:

In the resting position, the flap blocks the orifice in the casing, against which it is normally held by the simple effect of its weight. When the air-plus-acetylene mixture has been lit, the explosion forces the flap violently against the casing, the flap rebounds under the shock and is violently flung upwards so as to allow a sudden entry of air which contributes towards the creation inside the burner, then inside the chimney, of a rising air-current leading to the satisfactory formation of the shock wave. The flap then drops, oscillates a few times against the wall, an then takes up its equilibrium position, ready to serve for a new explosion.

According to a preferential characteristics of the invention, the fiap carries a device so designed that in the resting position, that is to say in its low position, while the flap is free to move around a horizontal axis situated above the casing orifice, the said flap is not exactly flush against the wall but forms a certain angle with the latter, usually between 10 and 45 and in the preferred case, between 15 and 30.

Such a device can be conceived in different ways and notably in a very simple manner, by designing a flap with a counter-weight system, or with a spiral spring mounted on the flap axis, arranged in such a way as to maintain the flap in the resting position, in such a way that the angle formed with the wall, is close to the desired preferred angle of 20.

Another item which is important in the cannon design and to the working of the invention is the relationship for a given height of the explosion chamber between the bumer diameter D, the wide part in which the explosion occurs, and diameter d of the retracted part of the truncated conical chimney above the burner. It has, in effect, been noticed that the maintenance of such a ratio, within the limits defined, between 4 and 2.5 for a burner height equal to approximately 3 times its diameter conditions simultaneously the efficiency and the safety of the system. If D/d is greater than 4, the diameter D becomes too large with reference to d, that is to say that the angle formed by the conical part of the burner in relation to the horizontal part becomes too small; as a result the energy released by the explosion has a tendancy to be driven downwards thus lowering the shock wave efficiency.

If D/d is less than 2.5, the diameter of the retracted portion, under the same conditions, is too large and the formation of an efficient shock wave takes place in a less satisfactory manner. According to a preferred characteristic of the invention the cannon for the working of the process will be fitted, between the summit of the upper retracted part of the burner and the retracted base of the conical truncated chimney, with a cylindrical portion to ensure the joint between these two parts. It has indeed been noticed that the presence of such a cylindrical part ensures a better efficiency in the shockwave obtained. The introduction of acetylene into the burner can be achieved by any convenient means, notably by simultaneous injection of a precalculated mixture of air and acetylene by means of one, or several, classic-type injectors such as those used in oxyacetylene welding torches.

In this case, the injector(s) is (are) directly connected to an acetylene source, for example a commercially available cylinder, by means of a tube which can be fitted with a convenient regulator device such as an electro-valve, pressure valve, or any other automatic device, electric, or preferably mechanical, so as to hinder the arrival of acetylene when a suitable volume has already been injected into the burner. Such a device can, moreover, be used in double, or multiple, identical circuits or different circuits mounted in parallel and ready to act in case of failure of the first device.

The acetylene can also be injected without air premixing, the mixture taking place in the burner because of the presence of the flap whose role and function has been described previously. In this latter case, the acetylene will be introduced, according to the preferred conditions, into the burner by means of a tube making spurts into the interior of the burner, oriented downwards and with the lower extremity situated essentially at the level of the air intake so as to obtain a homogeneous mixture. Such an arrangement will facilitate a homogeneous mixture the acetylene being lighter-thanair having a tendancy to rise and an efficient explosion thus giving results rise to an optimum shock wave. The ignition system can be any suitable device, mechanical, electric, piezo-electric, and more generally, any system likely to give rise to a flame at the required moment, or to a spark sufficient to ignite the mixture. This mixture being particularly inflammable, the required ignition is achieved very easily by sparking; for example with a spark-plug of the type used in internal combustion engines, or with a piezo-electric quartz, or with a resistance brought to red-heat. Another system consists in maintaining a pilot-flame, running on acetylene, buming permanently outside the burner. This pilot-flame is positioned a few centimeters from a small opening in the burner and, when an explosion is to be set off a quantity of acetylene is injected into the pilot thus giving rise to a longer flame which passes into the burner by the opening and ignites the mixture.

A mode of construction for a cannon working according to the procedure of the present invention will now be described in detail by reference to FIGS. 2, 3 and 4A, B, C.

Example I The cannon is composed of a burner 21 made of mm plate, constituting a cylindrical part 22 45 cm in diameter (D) on to which is welded a base 23 bearing in its center portion a a small opening 24 at the base to allow the automatic removal of water likely to accumulate in the burner base.

The height of the cylindrical part is 100 cm. At the upper extremity, for example, a truncated conical section is welded; this section, of which the narrow part is 16 cms in diameter, and bears circular flange 26 with openings designed to accomodate bolts which allow the fixation on the one hand of the cannon assembly system 27 and on the other hand of the truncated conical chimney 28, itself fitted with a flange 29 at its lower end.

The chimney is 4 meters in height and the shape of the interior of the lower part is such that it forms with the upper part of the conical part of the burner, a cylinder 30 approximately 12 cms in height, the utility of which has been previously explained.

There is an opening 31 of approximately cm in cross section in the lower part of the burner. The flap (not shown) which is free to move along a horizontal axis placed above the opening, is in the interior of the burner. The said flap drops into position so as to block the said opening. This flap is fitted with a counterpoise system arranged in such a way that in its lower position the flap makes an angle of 20 with the burner casing.

Two other openings 32 & 33 exist on the burner wall. The first is positioned beside the pilot jet 34 and is used for the ignition of the mixture at the opportune moment. The second 33 is used as an entry for the acetylene-admission pipe 35 and is directed from above towards the base within the burner, leading downwards over a length of 20 cms.

The inlet pipe 35 is joined to a control unit 36 by means of a three-way valve 37, itself joined on the one end to the pilot-jet 34 and on the other end to an acetylene source, comprising, for example, a commercially available acetylene cylinder 38.

This valve has a permanent flow passage which allows a direct link between cylinder and pipe 34 thus continuously feeding the pilot jet.

The control unit 36 is made up by a bell-form 39 which descends below water contained in a cylindrical tank 40 whose diameter is slightly larger than that of the submersible bell.

The functioning of the cannon is now explained by the reference to the three possible positions A B C of the valve 37 represented in FIG. 4.

In position A the acetylene cylinder feeds the regulator. The bell-form 39 rises to a certain height corresponding to the volume of acetylene which is to be admitted into the burner (5 10 liters). A visual controlsystem is used to confirm that the desired volume is attained. In position B the volume of acetylene accumulated within the feed regulator is injected into the burner by tube 35. In position C a complementary quantity of acetylene is injected suddenly into the pilot jet, the resulting flame penetrates into the cannon through the opening 32 and ignites the air-acetylene mixture. The resultant explosion sends a shock wave towards the sky via the chimney 28 and repetition, at the indicated frequency causes a modification of the cloud structure, notably avoiding hail. After this explosion, the cannon is ready to recommence a new cycle.

The working of the above-described cannon can either be manual or automatic with numerous possible variations concerning the acetylene-feed or the ignition system.

EXAMPLE 2 According to the mode of working represented in FIG. 5, acetylene injection is achieved by an injector 41', forming an air-acetylene mixture automatically; this injector is joined to an acetylene source (not shown) by a tube 42 in which an electro-valve 43 is interposed which itself is controlled by a time-switch 44 governing simultaneously acetylene in-flow and ignition.

In this given case, the time-switch is of the electronic resetting type which provides, in its first position, for the opening during a given time of the electro-valve metering acetylene in-flow and, in a second setting, the closing-down of the feed circuit which, by means of a contact-breaker 45 and a coil 46 causes a spark across the plug 47, such as an automobile-type spark plug, thus causing ignition of the mixture.

It is clear that the time switch, the electro-valve and the spark plug ignition system are fed by a convenient source of electrical energy, either by battery 48 or by another usual source of electrical energy.

Example 3 This mode of working corresponds to an automatic version of the device described in Example 1 (FIG. 6).

Acetylene arrives by tube 49, feeding in part the pilot jet by the tube 51 on which a non-retum valve 52 is fitted for safety reasons and, in part, one or several injectors 53 placed opposite to the opening 54in the burner wall 55. A three-way electro-valve 56 is fitted to the acetylene inlet tube. Valve rotation is by means of a motor 57, itself controlled by a time-switch 58, fed from a convenient source of current 59.

The two devices described in Examples 2 and 3 have the advantage of entirely automatic working. The possibility of current supply from an independent source, such as a battery, allows easy installation on sites which are not supplied with normal alternating current. This is frequently the case when the device is to be placed in a crop center to be protected such as orchards, vineyards, tobacco, etc.

The use of one of these devices under practical conditions has given extremely striking results against hail storms.

The process described in the invention must be started up as soon as hail-bearing clouds gather in the area to be protected. Explosions are set of every ten to fifteen seconds either manually or automatically and very rapid visual modification of the cloud structure is noted. Hail formation is thereby avoided. Shots are fired until every threat of hail has disappeared.

The protection thus acquired covers a minimum area of 50 to 100 hectares. Protection over a larger surface can be obtained by setting off more powerful explosions with a cannon of a convenient type.

The working of the said process is achieved in a particularly advantageous and economic manner using an air-acetylene mixture, but it is clear that any explosion of sufiicient force, occuring within the burner at the frequency indicated above, will give identical results. Among the sources of energy that are available, mention can be made of liquified gases such as methane, butane or propane, explosives and in general any product or compositions likely to give rise to a chemical reaction releasing sufficient energy either spontaneously, or in mixture with another product or another composition.

We claim:

1. A process for the transformation of the internal structure of visible cloud banks to avoid hail-storms,

COmpl'lSlflg I igniting an explosive composition to create a sudden upward movement of energy directed to form shock waves at cloud level, and repeating said igniting step at time intervals of less than 25 seconds for a period of time sufficient to modify the internal structure of visible cloud banks at the cloud level to avoid hail-storms.

2. A process according to claim 1 wherein said time interval between said igniting steps is between 8 and 15 seconds.

3. A process in accordance with claim 1 wherein said explosive composition is acetylene.

4. An apparatus to perform the process in claim 1 comprising a burner means for providing a chamber for carrying out explosions, inlet means for injecting air and explosive compositions into said burner means, ignition means for igniting said explosive composition in said burner means and a truncated conical chimney joined to said burner means for directing the shock waves to the cloud level.

5. An apparatus in accordance with claim 4 wherein said burner means includes a wide portion and a retracted narrow portion and wherein said truncated conical chimney is joined to said retracted narrow portion of said burner.

6. An apparatus in accordance with claim 5 wherein the ratio of the diameter of said wide portion to said retracted narrow portion is between 4:1 and 2.511.

7. An apparatus in accordance with claim 6 wherein said ratio of the diameters of said wide portion to said retracted narrow portion is between 3.5:1 and 2.721.

8. An apparatus in accordance with claim 4 wherein said truncated conical chimney has a cylindrical portion at the joint of said burner means of a length between 4 and 20 cm.

9. An apparatus in accordance with claim 8 -wherein said cylindrical portion has a diameter that lies between 13 and 20 cm.

10. An apparatus in accordance with claim 4 wherein said inlet means includes a flap means for closing said inlet means upon ignition of said air and explosive composition when in one mode, and for opening said inlet means for injection of air and explosive compositions in predetermined quantities when in a second mode.

11. An apparatusin accordance with claim 4 further including a double position electric time-switch of the automatic resetting type wherein said switch actuates said inlet means in one position and actuates said ignition means in another position.

12. A process in accordance with claim 1 wherein said igniting is done electrically and automatically at said preselected time interval.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3,848,301 Dated November 19, 1974 Inventor-( t 81 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 40, "are" should read -area-- Column 2, line 40, "How-control" should read --flow-control-- Column 3, line 31, "interval" should read "internal-- Column 4, line 6, "prakis" should read praxis-- Column 5, line 56, after "Figs. 2, 3" insert 4-- Column 6, line 12 "cm" should read --cm Signed and sealed this 24th day of June 1975.

(SEAL) Attest:

C. Y'iARSHALL DANN RUTH C. ILRSON Commissioner of Patents Attesting Officer and Trademarks ORM PO-105O (10-69) USCOMM-DC 60376-P69 U.S. GOVERNMENT FIINYING OFFICE "I, 0-366-334 

1. A process for the transformation of the internal structure of visible cloud banks to avoid hail-storms, comprising igniting an explosive composition to create a sudden upward movement of energy directed to form shock waves at cloud level, and repeating said igniting step at time intervals of less than 25 seconds for a period of time sufficient to modify the internal structure of visible cloud banks at the cloud level to avoid hail-storms.
 2. A process according to claim 1 wherein said time interval between said igniting steps is between 8 and 15 seconds.
 3. A process in accordance with claim 1 wherein said explosive composition is acetylene.
 4. An apparatus to perform the process in claim 1 comprising a burner means for providing a chamber for carrying out explosions, inlet means for injecting air and explosive compositions into said burner means, ignition means for igniting said explosive composition in said burner means and a truncated conical chimney joined to said burner means for directing the shock waves to the cloud level.
 5. An apparatus in accordance with claim 4 wherein said burner means includes a wide portion and a retracted narrow portion and wherein said truncated conical chimney is joined to said retracted narrow portion of said burner.
 6. An apparatus in accordance with claim 5 wherein the ratio of the diameter of said wide portion to said retracted narrow portion is between 4:1 and 2.5:1.
 7. An apparatus in accordance with claim 6 wherein said ratio of the diameters of said wide portion to said retracted narrow portion is between 3.5:1 and 2.7:1.
 8. An apparatus in accordance with claim 4 wherein said truncated conical chimney has a cylindrical portion at the joint of said burner means of a length between 4 and 20 cm.
 9. An apparatus in accordance with claim 8 wherein said cylindrical portion has a diameter that lies between 13 and 20 cm.
 10. An apparatus in accordance with claim 4 wherein said inlet means includes a flap means for closing said inlet means upon ignition of said air and explosive composition when in one mode, and for opening said inlet means for injection of air and explosive compositions in predetermined quantities when in a second mode.
 11. An apparatus in accordance with claim 4 further including a double position electric time-switch of the automatic resetting type wherein said switch actuates said inlet means in one position and actuates said ignition means in another position.
 12. A process in accordance with claim 1 wherein said igniting is done electrically and automatically at said preselected time interval. 